In flat panel display apparatuses, Thin Film Transistor Liquid Crystal Display (TFT-LCD) are characterized in small volume, low power consumption, relatively low production cost, no radiation, and the like, and thus predominates in the current market of flat panel displays.
Currently, the primary structure of TFT-LCD comprises an array substrate and a color filter (CF) substrate assembled together. Among others, the color filter substrate comprises primarily a glass substrate, a Black Matrix (BM), a color photoresist, and a protective film. In general, the Black Matrix is arranged in a manner of grating, stripe, or speckle among the color patterns formed from the color photoresist. The primary function of Black Matrix is to improve the contrast by inhibiting the mixing of colors, as well as to provide a shield against stray light so as to prevent the malfunction of TFT caused by light leakage among pixels.
A photoresist composition for Black Matrix undergoes coating, exposure, and development to form Black Matrix. The current photoresist composition for Black Matrix comprises a black pigment paste, photo-polymerizable monomers, photoinitiators, and an organic solvent, wherein the black pigment paste serves primarily to form a black color for preventing light leakage; and the photoinitiators induce a polymerization reaction of the photo-polymerizable monomers under UV radiation to form a polymeric film. The Black Matrix layer is required to possess a high light shielding property. However, BM is commonly prepared in an earlier procedure, which is followed by procedures of preparing the color photoresist, the protective layer, etc. Thus, the process technology of production line, as well as other factors including particles, impurities and the like will affect the BM layer and cause scratching damages leading to light leakage of damages and formation of white defects, thereby affecting the quality of TFT-LCD products. For avoiding such defects, the current process has to comprise a repair procedure after completing the preparation of Black Matrix, as shown in FIGS. 1a to 1c, that is, a schematic flowchart of the current process of preparing Black Matrix. Among others, FIG. 1a indicates that damages appear in some sites after a photoresist composition for Black Photoresist is applied; FIG. 1b indicates that white defects are formed at the damaged sites of the Black Matrix after the photoresist composition for Black Matrix undergoes laser radiation; and FIG. 1c indicates that the formed white defects are repaired by means of a repair procedure which can repair the defects by adding the photoresist composition for Black Matrix onto the damaged sites and allowed the added photoresist composition to be cured.
The current technology has a disadvantage that when white defects appear in the Black Matrix, a specific repair procedure and additional devices are required to add the photoresist composition for Black Matrix, thereby increasing the cost.